Thames River Conditions - 2012

[Watergeus]

Jubilee River

With the river once again at very high levels, does anyone understand how the EA operate the Jubilee River?

At present, with the level below many locks nearly a metre above normal levels, the level in the Jubilee River is recorded as 0.88m _below_ the normal level. Any idea what's the purpose of this?

You can see the recent history at http://www.environment-agency.gov.uk/homeandleisure/floods/riverlevels/136496.aspx?stationId=7164

I had a look recently at the inlet and outlet of this waterway: the inlet had one gate out of three letting through water; the outlet is a set of fixed height V-weirs, which obviously doesn't permit much control. The recorded height has big dips at about 24 hour intervals, which suggests that the gates can only operate in a fully closed or fully open position.

Now clearly as well as avoiding floods in the Windsor area (it wouldn't do, would it) the EA also has to be careful of not flooding the reaches from Old Windsor downwards and these are already up to flood levels. So it seems that in these conditions the river has very little function.

So what good does it do?

 

[supersparky]

With the river once again at very high levels, does anyone understand how the EA operate the Jubilee River?

At present, with the level below many locks nearly a metre above normal levels, the level in the Jubilee River is recorded as 0.88m _below_ the normal level. Any idea what's the purpose of this?

You can see the recent history at http://www.environment-agency.gov.uk/homeandleisure/floods/riverlevels/136496.aspx?stationId=7164

I had a look recently at the inlet and outlet of this waterway: the inlet had one gate out of three letting through water; the outlet is a set of fixed height V-weirs, which obviously doesn't permit much control. The recorded height has big dips at about 24 hour intervals, which suggests that the gates can only operate in a fully closed or fully open position.
Now clearly as well as avoiding floods in the Windsor area (it wouldn't do, would it) the EA also has to be careful of not flooding the reaches from Old Windsor downwards and these are already up to flood levels. So it seems that in these conditions the river has very little function.
So what good does it do?

Jubilee River can be used as a sink to divert water away from the Thames if levels become excessive. Meantime at Teddington the weirs are fully open to drop the level above as low as possible so that the next lock at Molesey can be opened without flooding Kingston and Thames Ditton; and so on up the stream. E.A. so far seem to be doing the best that can be done but will that be enough in this exceptional month? High Tide at Teddington can be problematic as the river backs up, flooding Kingston for an hour or two and we are coming up to next Spring tides (higher than usual tides at full moon and new moon).
On Monday 31st just after 1700 the predicted tide of 4.8 metres will back up the river to cause flooding up to Thames Ditton; could this be mitigated by closing the Thames barrier? What are the unintended consequences? The Thames Water pumping station at Sunbury can pump into various reservoirs but that makes little difference. River at Kingston is 2.5m deep X 80m wide at 4kts (1.8m/sec = approx 100m/min). 2.5 X 80 X 100 = 20,000 tonnes/min or 1.2M ton/hr. Boats can be lifted onto the banks, Keep your lines slack with long springs to allow for the rise and fall. The E.A. are earning their salaries with sleepless nights and nailbiting days. Good luck to all. My boat is on the Medway!

 

[Watergeus]

Thanks Sparky. I agree the EA is doing a good balancing act! The Thames Barrier has already done its job once and will presumably be used again. I see the tide on Sunday is predicted at only 6.9m so at least that's not excessive.

But there's a LOT of water in the Thames. The levels much of the way up the river have exceeded the "recent" record heights, which go back up to 10 years, and given that rain is continuing I can't see them going down quickly, unlike November. Mercifully in the last 24 hours most of them have started to go down and the forecasts for the weekend tend to suggest that the west country will get the worst of it, tho rainfall ain't that predictable.

Despite the fact that the Jubilee River isn't taking much water, it does seem to be protecting Maidenhead and Bray pretty well, Windsor not quite so well (I'm not sure why). But obviously Staines, Chertsey, Sunbury etc. are in danger of flooding, as well as any threat from tides.

 

[teddington_lock]

Barrier has been in for the last two tides. Tides are building now until NYE , so I suspect it will probably be in again over the next few days.

 

[boatone]

Couple of EA tweets on twitter in the last few hours:

"Environment Agency ‏@EnvAgency
We used the #Thames Barrier to protect London from flood for the 120th time since 1982 today. The last time was in March '10"

"Looks like we will be closing the #thames #barrier again for the next tide due to the high flows in the #thames."

 

[capnfishy]

Jubilee River

The best person(s) to ask about the operation of the Jubilee is the men wot does it, Ralph the Lockie at Boulters or Keith at Bray.

 

[boatone]

I have asked the mods to "unstick" this thread and replace with the new 2013 thread.
Bye bye 2012 !